Quantitative PCR and Fluorescent Oligonucleotide to 1Gs rDNR for Detection of Oral Spirochetes Spirochetes as a group comprise a large portion of the subgingival plaque bacterial flora involved in periodontal diseases. The role of spirochetes in periodontal diseases is not understood. This lack of knowledge concerning the role of spirochetes in oral ecology relates to difficulty in culturing and enumerating individual spirochete species. Molecular techniques will be developed for rapid quantitation of individual spirochete species from subgingival plaque samples. These techniques will be used in pilot clinical studies to begin to assess the correlations between the abundances of spirochetes in general, individual spirochete species, and periodontal diseases. This is a critical step towards understanding the roles of spirochetes in periodontal diseases. The molecular approach is to use a coupled PCR-fluorescent oligonucleotide probe analysis to simultaneously estimate the relative abundances of several individual oral spirochete species, the total spirochete population, and the total eubacterial population in a subgingival plaque samples. Pilot clinical studies are planned to provide initial information correlating particular spirochete species to certain periodontal diseases. This is a first step towards designing meaningful clinical studies where well-defined periodontal disease states or diseases activity are correlated with abundances of specific spirochetes. The long-term objective is to use the data from the pilot clinical studies to develop an appropriate full-scale clinical study aimed at understanding the ecology of oral spirochetes as it related to periodontal diseases. Also, it is anticipated that the analytical technique under development may have wide applicability to studies of other bacteria in natural samples. KEYWORDS: Treponemes, PCR, Phylogeny, DNA Probes